DM-domain (Zn-finger motif domain) genes play an important role in the sex determination and differentiation among animal kingdom. In the present study, the gene of Doublesex (Cqdsx) was identified and characterized for the first time in the redclaw crayfish, Cherax quadricarinatus. The full-length cDNA was 1271 bp, comprising a 155 bp 5′-untranslated region (5′-UTR), an 885 bp predicted open reading frame (ORF) encoding 294 amino acid polypeptides, and a 231 bp 3′-UTR. The deduced amino acid sequence of Cqdsx was predicted to contain a highly conserved DM domain and shared nearly 50% identity to DM-peptides from other species. The results of quantitative Real-time PCR in various tissues revealed that Cqdsx was strongly expressed in gonads, while was almost undetectable in gill, heart, hepatopancreas, muscle and intestine. Comparing expression level in different embryonic stages found that Cqdsx was gradually increased with the development of the embryos. In situ hybridization to gonad sections showed that intensive hybridization signals were mainly observed in oocytes and ovarian lamellae and weak signals were detected in spermatocyte. Additionally, Cqdsx gene exhibited higher transcript levels in the early stage of ovarian development. Furthermore, RNAi-targeting Cqdsx silencing induced a decrease of Cq-IAG trascripts, which regulate the male sexual differentiation in crustaceans. Taken together, these findings strongly suggest an essential role for Cqdsx in the female ovarian development/differentiation of the redclaw crayfish.

DM结构域（锌指基序结构域）基因在性别决定和动物界分化中起重要作用。在本研究中，首次在红爪小龙虾Cherax quadricarinatus中鉴定并鉴定了Doublesex（Cqdsx）基因。全长cDNA为1271 bp，包含155 bp的5'-非翻译区（5'-UTR），885 bp的预测开放阅读框（ORF），编码294个氨基酸多肽，以及231 bp的3'-UTR。据推测，Cqdsx的推导氨基酸序列包含高度保守的DM结构域，与来自其他物种的DM肽具有近50％的同一性。在各种组织中进行实时定量PCR的结果表明，Cqdsx在性腺中强烈表达，而在g，心脏，肝胰腺，肌肉和肠中几乎检测不到。比较不同胚胎阶段的表达水平发现，Cqdsx随着胚胎的发育而逐渐增加。与性腺切片的原位杂交表明，在卵母细胞和卵巢片中主要观察到强烈的杂交信号，在精母细胞中检测到弱信号。此外，Cqdsx基因在卵巢发育的早期阶段表现出较高的转录水平。此外，靶向RNAi的Cqdsx沉默诱导Cq-IAG降低脚本，调节甲壳类动物的男性性别分化。综上所述，这些发现强烈暗示了Cqdsx在红爪小龙虾的女性卵巢发育/分化中的重要作用。